package com.hp.test.interview.recursion;

import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

/**
 * Date 03/03/2016
 *
 * @author Tushar Roy
 * <p>
 * Remove the minimum number of invalid parentheses in order to make the input string valid.
 * Return all possible results
 * <p>
 * Reference
 * https://leetcode.com/problems/remove-invalid-parentheses/
 */
public class RemoveInvalidParenthesis {

    public static void main(String args[]) {

        String s = "(r(()()(";
        RemoveInvalidParenthesis rmp = new RemoveInvalidParenthesis();
        List<String> result = rmp.removeInvalidParentheses(s);
        result.forEach(s1 -> System.out.println(s1));
    }

    public List<String> removeInvalidParentheses(String s) {
        Set<String> res = new HashSet<>();
        int rmL = 0, rmR = 0;
        for (int i = 0; i < s.length(); i++) {
            if (s.charAt(i) == '(')
                rmL++;
            if (s.charAt(i) == ')') {
                if (rmL != 0)
                    rmL--;
                else
                    rmR++;
            }
        }
        DFS(res, s, 0, rmL, rmR, 0, new StringBuilder());
        return new ArrayList<String>(res);
    }

    public void DFS(Set<String> res, String s, int i, int rmL, int rmR, int open, StringBuilder sb) {
        if (i == s.length() && rmL == 0 && rmR == 0 && open == 0) {
            res.add(sb.toString());
            return;
        }
        if (i == s.length() || rmL < 0 || rmR < 0 || open < 0)
            return;

        char c = s.charAt(i);
        int len = sb.length();

        if (c == '(') {
            DFS(res, s, i + 1, rmL - 1, rmR, open, sb);
            DFS(res, s, i + 1, rmL, rmR, open + 1, sb.append(c));

        } else if (c == ')') {
            DFS(res, s, i + 1, rmL, rmR - 1, open, sb);
            DFS(res, s, i + 1, rmL, rmR, open - 1, sb.append(c));

        } else {
            DFS(res, s, i + 1, rmL, rmR, open, sb.append(c));
        }

        sb.setLength(len);
    }
}
